Mortgage meltdown/Credit crunch

An interesting blog by an IFA is linked here, on which I found this: Historic Northen Rock e-mail I dug out an old e-mail from Northern Rock from July 2007 with this paragraph of interest. Our Fast Track Guarantee for cases up to 85% LTV we will guarantee not to request verification of your client's income, provided that they meet our criteria upon submitting their application (please refer to the Mortgage Update for full details). Now I wonder why they would guarantee not to check incomes?